In the prior art, there has been developed an assembly consisting of a dipper stick connectable to the boom of a machine such as an excavating machine, a tool typically a bucket, pivotally connected to the dipper stick, a cylinder assembly operatively interconnecting the dipper stick and the tool for pivoting the tool and an arm member mounted on and depending from the underside of the dipper stick, commonly referred to as a “thumb”, cooperable with the tool when the tool is pivoted toward the arm member for grappling objects such as trees, logs, large rocks and the like therebetween. Such an assembly is illustrated and described in U.S. Pat. No. 3,613,922.
For such an assembly to operate effectively in performing grappling operations, such arm member should lie in substantially the same vertical plane as the dipper stick and tool and be aligned with the tool to most effectively grapple an object between the tool and the arm member. Often, however, in the operation of such machines, lateral forces may be applied to such arm members which could have the effect of misaligning the arm member with a tool and, with the application of severe forces, possibly breaking the arm member from the dipper stick. Accordingly, it is the principal object of the present invention to provide an arm member of a grappling assembly which will withstand laterally directed impact forces, prevent breakage and restore it in proper alignment with the cooperating tool of the assembly for grappling objects.